engine coolant MITSUBISHI LANCER EVOLUTION X 2008 User Guide

SENSOR
MULTIPORT FUEL SYSTEM (MFI)13A-10
ENGINE COOLANT TEMPERATURE SENSOR
The engine coolant temperature sensor is installed in the ther-
mostat housing. Engine coolant temperature sensor uses ther-
mistor's resistance change to detect coolant temperature and
output the voltage according to coolant temperature to ECM.
ECM uses this output voltage to appropriately control fuel injec
-
tion volume, idle speed and ignition timing. Sensor properties
are as shown in the figure.
.
THROTTLE POSITION SENSOR
The throttle position sensor is installed in the throttle body.
Throttle position sensor outputs voltage to ECM based on the
throttle shaft rotation angle. ECM uses this signal to detect the
throttle valve opening angle to perform throttle actuator control
motor feedback control. This throttle position sensor uses Hall
IC and is a non-contact type.
.
AK602255AC
Sensory part
(thermistor)
AK602208
Engine coolant
temperature C (F)
AG
Output voltage V
5V Engine coolant
temperature sensor
(thermistor)
Engine coolant
temperature C (F) ECM
Resistance kΩ
AK604120AB
Throttle body
Throttle
position
sensor

FUEL INJECTION CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-29
FUEL INJECTION CONTROLM2132003001036
Fuel injection volume is regulated to obtain the opti-
mum air-fuel ratio in accordance with the constant
minute changes in engine driving conditions. Fuel
injection volume is controlled by injector drive time
(injection time). There is a prescribed basic drive
time that varies according to the engine speed and intake air volume. ECM adds prescribed compensa
-
tions to this basic drive time according to conditions
such as the intake air temperature and engine cool
-
ant temperature to decide injection time. Fuel injec-
tion is done separately for each cylinder and is done
once in two engine rotations.
System Configuration Diagram
1. INJECTOR ACTUATION (FUEL INJECTION)
TIMING
Injector drive time in case of multiport fuel injection (MFI) is
controlled as follows according to driving conditions.
AK604128AB
ECM InjectorMass airflow sensor
Intake air temperature sensor
Manifold absolute
pressure sensor
Engine coolant
temperature sensor
Accelerator pedal position sensor
Knock sensor
Intake camshaft position sensor
Ignition switch-ST
Heated oxygen sensor (front, rear) Crankshaft position sensor

FUEL INJECTION CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-32
Fuel Injection Volume Control Block Diagram
.
AK602278AD
Mass airflow sensor
Crankshaft
position sensor
Heated oxygen
sensor
Engine coolant
temperature
compensation Engine coolant
temperature sensor
Manifold absolute
pressure sensorFuel pressure
compensation Barometric pressure
sensor
Battery voltage
compensation Battery voltageBasic fuel
injection time
determinationAir fuel ratio
compensation
(Predetermined
compensation)
Heated oxygen
sensor feedback
compensation
Injector Acceleration-
deceleration
compensation

FUEL INJECTION CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-33
[Injector basic drive time]
Fuel injection is performed once per cycle for each cylinder.
Basic drive time refers to fuel injection volume (injector drive
time) to achieve theoretical air-fuel ratio for the intake air vol
-
ume of 1 cycle of 1 cylinder. Fuel injection volume changes
according to the pressure difference (injected fuel pressure)
between manifold absolute pressure and fuel pressure (con
-
stant). So, injected fuel pressure compensation is made to
injector drive time for theoretical air-fuel ratio to arrive at basic
drive time.
Intake air volume of each cycle of 1 cylinder is calculated by
ECM based on the mass airflow sensor signal and crankshaft
position sensor signal. Also, during engine start, the map value
prescribed by the engine coolant temperature sensor signal is
used as basic drive time.
.
AK602279AC
Basic fuel
injection timeFuel injection pressure compensation Intake air amount per cycle per cylinder
Theoretical air-fuel ratio

FUEL INJECTION CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-34
[Injector drive time compensation]
After calculating the injector basic drive time, the ECM makes
the following compensations to control the optimum fuel injec
-
tion volume according to driving conditions.
List of main compensations for fuel injection control
.
[Fuel limit control during deceleration]
ECM limits fuel when decelerating downhill to prevent exces-
sive rise of catalytic converter temperature and to improve fuel
efficiency.
.
[Fuel-cut control when over-run]
When engine speed exceeds a prescribed limit (6,600 r/min),
ECM cuts fuel supply to prevent overrunning and thus protect
the engine. Also, if engine speed exceeds 4,000 r/min for 15
seconds while vehicle is stationary (no load), it cuts fuel supply
and controls the throttle valve opening angle to protect the
engine.
CompensationsContent
Heated oxygen sensor feedback compensationThe heated oxygen sensor signal is used for
making the compensation to get air-fuel ratio with
best cleaning efficiency of the 3-way catalytic
converter. This compensation might not be made
sometimes in order to improve drivability,
depending on driving conditions. (Air-fuel ratio
compensation is made.)
Air-fuel ratio compensationUnder driving conditions where heated oxygen
sensor feedback compensation is not performed,
compensation is made based on pre-set map
values that vary according to engine speed and
intake air volume.
Engine coolant temperature compensationCompensation is made according to the engine
coolant temperature. The lower the engine coolant
temperature, the greater the fuel injection volume.
Acceleration/ Deceleration compensationCompensation is made according to change in
intake air volume. During acceleration, fuel injection
volume is increased. Also, during deceleration, fuel
injection volume is decreased.
Fuel injection compensationCompensation is made according to the pressure
difference between atmospheric pressure and
manifold absolute pressure. The greater the
difference in pressure, the shorter the injector drive
time.
Battery voltage compensationCompensation is made depending on battery
voltage. The lower the battery voltage, the greater
the injector drive signal time.
Learning value for fuel compensationCompensation amount is learned to compensate
feedback of heated oxygen sensor. This allows
system to compensate in accordance with engine
characteristics.

IGNITION TIMING AND CONTROL FOR CURRENT CARRYING TIME
MULTIPORT FUEL SYSTEM (MFI)13A-35
IGNITION TIMING AND CONTROL FOR CURRENT
CARRYING TIME
M2132027100089
Ignition timing is pre-set according to engine driving
conditions. Compensations are made according to
pre-set values depending on conditions such as
engine coolant temperature, battery voltage etc. to
decide optimum ignition timing. Primary current con
-
nect/disconnect signal is sent to the power transistor
to control ignition timing. Ignition is done in sequence
of cylinders 1, 3, 4, 2.
System Configuration Diagram
AK502722AD
ECM MFI relay
Spark plugs Ignition
coils
Cylinder No. 1 2 3 4Battery
Mass airflow sensor
Intake air temperature sensor
Manifold absolute
pressure sensor
Engine coolant
temperature sensor
Intake camshaft position sensor
Exhaust camshaft position sensor
Crankshaft position sensor
Knock sensor
Ignition switch-ST Throttle position sensor

IGNITION TIMING AND CONTROL FOR CURRENT CARRYING TIME
MULTIPORT FUEL SYSTEM (MFI)13A-37
2. Spark-advance control and current carrying
time control
.
[During start]
ECM initiates ignition at fixed ignition timing (5° BTDC) syn-
chronized with the crankshaft position sensor signal.
.
[During normal operation]
After determining the basic spark-advance based on the intake
air volume and engine speed, ECM makes compensations
based on input from various sensors to control the optimum
spark-advance and current carrying time.
List of main compensations for spark-advance control and current carrying time control
.
[Control for checking ignition timing]
During basic ignition timing set mode for M.U.T.-III actuator test
function, sparking is done with fixed ignition timing (5
° BTDC)
synchronized with crankshaft position sensor signal.
CompensationsContent
Intake air temperature compensationCompensation is made according to intake air
temperature. The higher the intake air temperature
the greater the delay in ignition timing.
Engine coolant temperature compensationCompensation is made according to engine coolant
temperature. The lower the engine coolant
temperature the greater the advance in ignition
timing.
Knocking compensationCompensation is made according to generation of
knocking. The greater the knocking the greater the
delay in ignition timing.
Stable idle compensationCompensation is made according to change in idle
speed. In case engine speed becomes lower than
target speed, ignition timing is advanced.
Delay compensation when changing shiftDuring change of shift, sparking is delayed
compared to normal ignition timing to reduce
engine output torque and absorb the shock of the
shift change.
Battery voltage compensationCompensation is made depending on battery
voltage. The lower the battery voltage the greater
the current carrying time and when battery voltage
is high current carrying time is shortened.

THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE SPEED CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-38
THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE
SPEED CONTROL
M2132003500328
ECM detects the amount of accelerator pedal
depression (as per operator's intention) through the
accelerator pedal position sensor. Based on pre-set
basic target opening angles it adds various compen
-
sations and controls the throttle valve opening angle
according to the target opening angle.
While starting
ECM adds various compensations to the target
opening angle that are set based on the engine cool
-
ant temperature, so that the air volume is optimum
for starting.
While idling
ECM controls the throttle valve to achieve the target
opening angle that are set based on the engine cool
-
ant temperature. In this way best idle operation is
achieved when engine is cold and when it is hot.
Also, the following compensations ensure optimum
control.
While driving
Compensations are made to the target opening
angle set according to the accelerator pedal opening
angle and engine speed to control the throttle valve
opening angle.
AK602236AE
Throttle
position
sensorMain
Main Sub
SubMotor drive circuit
A/C switch (CAN) Engine coolant
temperature sensor
Intake air temperature
sensor
Crankshaft position sensor
Power steering pressure
switch
Generator FR terminal
Transmission range
switch (CAN) Motor drive power supply
(From throttle actuator
control motor relay)
Throttle actuator
control motor
Control unit
Barometric pressure
sensor Accelerator
pedal position
sensor
ECM

THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE SPEED CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-39
List of main compensations for throttle valve opening angle and idle speed control
Initialize control
After ignition switch turns OFF, ECM drives the throt-
tle valve from fully closed position to fully open posi-
tion and records the fully closed/open studied value
of the throttle position sensor (main and sub) output
signals. The recorded studied values are used as
studied value compensation for compensating basic
target opening angle when the engine is started next.
CompensationsContent
Stable idle compensation (immediately after start)In order to stabilize idle speed immediately after
start, target opening angle is kept big and then
gradually reduced. Compensation values are set
based on the engine coolant temperature.
Rotation speed feedback compensation (while
idling)In case there is a difference between the target idle
speed and actual engine speed, ECM
compensates the throttle valve opening angle
based on that difference.
Atmospheric pressure compensationAt high altitudes atmospheric pressure is less and
the intake air density is low. So, the target opening
angle is compensated based on atmospheric
pressure.
Engine coolant temperature compensationCompensation is made according to the engine
coolant temperature. The lower the engine coolant
temperature the greater the throttle valve opening
angle.
Electric load compensationThrottle valve opening angle is compensated
according to electric load. The greater the electric
load, the greater the throttle valve opening angle.
Compensation when shift is in D range When transmission is changed from P or N range
to some other range, throttle valve opening angle is
increased to prevent reduction in engine speed.
Compensation when A/C is functioningThrottle valve opening angle is compensated
according to functioning of A/C compressor. While
A/C compressor is being driven, the throttle valve
opening angle is increased.
Power steering fluid pressure compensationThrottle valve opening angle is compensated
according to power steering functioning. When
power steering oil pressure rises and power
steering pressure switch is ON, the throttle valve
opening angle is increased.

HEATED OXYGEN SENSOR HEATER CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-49
HEATED OXYGEN SENSOR HEATER CONTROLM2132007000206
When exhaust gas temperature is low, the heated
oxygen sensor response is dull. So, response is
improved by raising the sensor temperature by pass
-
ing current through the heater at a low exhaust gas
temperature, such as in the immediate aftermath of
the engine start, or during the warm up operation and in cutting the fuel during deceleration. Based on driv
-
ing conditions and the heated oxygen sensor activa-
tion state, ECM changes the amount of current (duty
ratio) to the heater to quicken the activation of the
heated oxygen sensor.
AK602241AD
Battery Heated oxygen sensor heater
Engine coolant
temperature sensor MFI relay
ECM